This SBIR Phase I project will evaluate an ultra-sensitive detection technology known as Surface Plasmon Enhanced Common Path Interferometry (SPE-CPI) in the rapid, label-free identification and quantification of cancer-related microRNAs in blood samples. MicroRNAs have gained considerable attention as potentially predictive biomarkers for a number of disorders. Mounting evidence suggests that miRNAs are differentially expressed in a variety of cancers and thus have potential for early detection, prognosis, and monitoring of response to treatment. Because of their small size and low concentrations, miRNAs in biological fluids will be demanding targets for detection, requiring advanced diagnostic technologies. SPE-CPI differs from standard Surface Plasmon Resonance (SPR) detection methods in that it combines the high sensitivity of SPR with the lower noise of single beam path (CPI). SPE-CPI can also simultaneously monitor multiple species of miRNA in a single sample.